Metallic stair.



G. SANDBLOM.

METALLIC STAIR.

APPLIGATION FILED no. 17, 1909.

INVENTOR JMOZALMM woe/m Patented June 7, 1910.

BY M I WITNESSES:

GUSTAV SANDBLOM, OF NEW YORK, N. Y.

METALLIC STAIR.

Specification of Letters Patent.

Patented June '7, 1910.

Application filed December 17, 1909. Serial No. 533,710.

To all whom 'it may concern:

Be it known that I, GUs'rAv SANDBLOM,

a citizen of the United States, residing at- New York city, Brooklyn, county of Kings State of New York, have invented new an useful Improvements in Metallic Stairs, of which the following is a specification.

This invention relates to an improved steel stairs construction and more particularly to improved means for securing the steps to the strings. In the accompanying drawing: Figure 1 is a vertical section of part of metallic stairs embodying my invention; Fig. 2 is a plan of the blank for forming one of the steps and Fig. 3 a rear View of the left edge of a series of consecutive steps.

Each metallic step is composed of a riser 10, a tread 11, and an'upright flange 12 at the back of the tread wh1ch is concealed by the riser of the ste next above, all as usual. The right and le ends of each tread 11 are provided with downwardly extending flanges 13, while the right and left ends 0 each riser 10 are provided with rearwardly extending flanges 14. The outer faces of flanges 13, 14 lie snugly against the inner faces of strings 15, to which they are riveted, as at 16. Each to flan e 12 is slightly shorter than its trea 11, being set back from both edges thereof. In this way there is formed at each end of flange 12, a recess 17 which accommodates the lower end of the flange 1 1 of the riser 10 pertaining to the step next above, so that the entire series of flanges 13, 14, on each side of the steps, are flush.

Each step is formed from an oblong steel plate illustrated in Fig. 2. This plate is punched to form the upper corner recesses 17, side nicks 18, and rivet holes 19. The plate is then bent on the dotted lines 20, 21, and 22, to form the tread, rlser, top flange and side flanges, all as above described.

It will be seen that with my improved stairs construction the steps are directly riveted to the strings, by means of integral flanges which are flush on each side of the steps. In this way the assemblage of parts is greatly facilitated and superior strength is insured.

Upon the treads 11, may be supported stone or other slabs 23, as usual.

I claim Metallic stairs comprisin steps each composed of a single iece of bent metal forming a riser, a tread a to flange at the back of the tread which is s ightly shorter than the length of the tread, and end flanges on the tread and riser, and strings to which said end flanges are secured.

Signed by me at New York city, (Manhattan,) N. Y., this 15th day of December,

GUSTAV SANDBLOM. Witnesses W. R. SCHULZ, FRANK v. Bnmsnn. 

